If you have experience writing about a topic you're not familiar with, share an example with the interviewer. If you don't have experience doing this, make sure to think about the approach you'd take before the interview, so you can explain it with confidence.

"I've written about many topics that were new to me. My first step is to do some online research and review several informative articles, blogs, and videos. I take notes and write down questions about aspects of the topic I'll need to further explore. Once I feel I have a good enough understanding to start writing, I'll develop an outline or draft and go from there. Most of the time, I can find everything I need online. Sometimes, however, I will go back to the client or subject matter expert to clarify some points."